Pre-treatment of Textile /Textile pretreatment process


DEFINITION:

Pretreatment means any treatment, which is done before actual (dyeing and printing) process. Textile pretreatment is the series of cleaning operations. All impurities which causes adverse effect during dyeing and printing is removed in pretreatment process.

AIM OF PRE-TREATMENT:
·         Conversion of fabric from hydrophobic to hydrophilic state.

·         To remove dust, dirt etc from the fabric.
·         To achieve the degree of desire whiteness.

CONSTITUENTS OF COTTON:
As discussed earlier pretreatment is the series of cleaning operations. In pretreatment all the impurities present in cotton are removed. Cotton fiber by nature contains:

Cellulose
86.8%
Natural Impurities:

Oil and Waxes
0.7%
Pectin’s
1.0%
Carbohydrates
0.5%
Proteins
1.2%
Salt
1.0%
Water
8.5%

Colour Pigments:
Others                                    2.0%

Except cellulose and water all the impurities are removed in pretreatment
                        IMPURITIES REMOVED DURING PRE-TREATMENT:
Short Fibres

Singeing
Applied Impurities
(Size Material)
Desizing
Artificial Impurities
(Oil, Strains, Dust, Dirt)
Scouring
Natural Impurities
(Oil, Wax, Pectin’s, Proteins)
Scouring
Colour Pigments
(Naturally present in cotton)
Bleaching


PRETREATMENT PROCESS OF COTTON FABRIC:
1-         Inspection of grey fabric. 2- Marking of grey fabric.
3-           Stitching.
4-           Shearing / Cropping. 5-            Singeing.
6-         Desizing (only for woven fabric) 7- Scouring.
8-         Bleaching.
All process discuss in detailed one by one.

1-INSPECTION OF GREY FABRIC:

After receiving the cloth from grey godown, it should be thoroughly checked and inspected before subjecting it to wet processing. The cloth is examined for the following:
2-FABRIC DEFECTS:
Oil, rust, stains, holes, damage selvedge and weaving faults like floats and read marks etc.
FABRIC SPECIFICATIONS:
Width, length, yarn count, ends and picks per inch and fabric composition.

3-MARKING OF GREY FABRIC:

Before carrying out any process, marks are made on the material for identification. For marking special inks are used capable of resisting all subsequent treatment which the material may have to go undergo.

4-STITCHING:

Small pieces of fabric are stitched together so as to form a continuous length, which is workable in the subsequent processes. The stitching must be very secure so that the fabric may run smoothly on various machines.

5-SHEARING / CROPPING:

Removal of fibres, tufts and loose threads from the surface of material by cutting them with blades on shearing or cropping machines. This process is carried out in open width. In this process tufts are not removed as closed as by singeing.

6-SINGEING:

Singeing is the process in which protruding fibres present on the surface of the fabric are removed. In order to achieve the smooth surface which facilitate printing.

7-DESIZING:

Desizing is the process in which size material is removed.

8-SCOURING:

Scouring is the process in which natural as well as artificial impurities are removed.

9-BLEACHING:


Bleaching is the process in which we remove the colour pigments in order to achieve the degree of whiteness.

10-MERCERIZATION:

Mercerization is the optional process or in on the customer requirement. Mercerization is done to achieve the luster, strength, more absorbent etc.

PRETREATMENT OF WOOL FIBRES:


Sequence of pretreatment of wool fibres a given below:
·         Scouring.
·         Carbonizing (remove the vegetable impurities)
·         Bleaching.

PRETREATMENT OF MAN-MADE FIBRES:

·         Desizing(if size material is applied)
·         Scouring.
·         Heating Setting.(dimensional stability)


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